#include<iostream>
#include<cstdio>

using namespace std;

int main()
{
    double a,b,c,d,e,f,g,n;
    cin>>a>>b>>c>>d>>e>>f>>g;
    n=a+b+c+d+e+f+g;
    printf("%.3lf",5040*a/n*b/(n-1)*c/(n-2)*d/(n-3)*e/(n-4)*f/(n-5)*g);
    return 0;
} 